1. Field of the Invention
The present invention generally relates to a vehicle on-board unit. More specifically, the present invention relates to a host vehicle having a vehicle on-board unit that communicates with other vehicle to increase the accuracy of a lane centerline determination of the road that the host vehicle is traveling.
2. Background Information
Recently, vehicles are being equipped with a variety of informational systems such as navigation systems, Sirius and XM satellite radio systems, two-way satellite services, built-in cell phones, DVD players and the like. These systems are sometimes interconnected for increased functionality. Various informational systems have been proposed that use wireless communications between vehicles and between infrastructures, such as roadside units. These wireless communications have a wide range of applications ranging from crash avoidance to entertainment systems. The type of wireless communications to be used depends on the particular application. Some examples of wireless technologies that are currently available include digital cellular systems, Bluetooth systems, wireless LAN systems and dedicated short range communications (DSRC) systems.
Dedicated short range communications (DSRC) is an emerging technology that has been recently investigated for suitability in vehicles for a wide range of applications. DSRC technology will allow vehicles to communicate directly with other vehicles and with roadside units to exchange a wide range of information. In the United States, DSRC technology will use a high frequency radio transmission (5.9 GHz) that offers the potential to effectively support wireless data communications between vehicles, and between vehicles, roadside units and other infrastructure. The important feature of DSRC technology is that the latency time between communications is very low compared to most other technologies that are currently available. Another important feature of DSRC technology is the capability of conducting both point-to-point wireless communications and broadcast wireless messages in a limited broadcast area.
Accordingly, wireless technology can be used to provide various information from vehicle-to/from-infrastructure, and from vehicle-to-vehicle. In vehicle safety applications, a “Common Message Set” (CMS) would mostly likely be developed in which a prescribed set of vehicle Parameter Identifiers (PIDs) are broadcast by each vehicle to give relevant kinematical and location information such as GPS location/vehicle position, vehicle speed, vehicle dimensions etc. The so called common message set can be broadcasted in three different way, i.e., event based broadcasting, periodic broadcasting and hybrid (event based/periodic) broadcasting. In event based broadcasting, no communications are conducted until a potential safety concern (event) is determined to exist. Once the event occurs, event specific messages will be sent out at a predetermined frequency (e.g., 10 Hz). In periodic broadcasting, each vehicle will send out a “heart beat” message at a predetermined frequency (e.g., 10 Hz). This “heart beat” message will contain all the information necessary for all the safety applications to function. In hybrid (event based/periodic) broadcasting, a “heart beat” message will be periodically sent at a predetermined lower frequency (e.g., 2-3 Hz) and an event specific message will be sent out once a potential safety concern (event) is determined to exist. In any case, once a potential safety concern is determined to exist, a warning system in the vehicles would notify the driver of the potential safety concern so that the driver can take the appropriate action. Thus, when communications are established with between vehicles and/or roadside units in close proximity, this information would be communicated to provide a complete understanding of the vehicles in the broadcast area. This information then can be used by the vehicles for both vehicle safety applications and non-safety applications.
Recently, a Vehicle Safety Communication Consortium (VSCC) was established to study safety applications of wireless communications. The Vehicle Safety Communication Consortium developed a list of safety applications that were believed to have the highest potential for reducing the number or mitigating crashes. During these studies, one particular application that was developed was called the Emergency Electronic Brake Light application (EEBL). In the Emergency Electronic Brake Light application, a vehicle-to-vehicle communication is established with an aim to prevent rear end crashes by communicating a hard braking event by a preceding vehicle to other vehicles in the vicinity. In this application, a vehicle can be notified of the hard braking event even if the driver cannot see the brake lights of the preceding vehicle, e.g. when a truck or a terrain obstacle is blocking the driver's view of the brake lights of the preceding vehicle. When the Emergency Electronic Brake Light application is employed, it is important to be able to determine if the incoming message of a hard braking event is relevant to the host vehicle receiving the incoming EEBL message. Thus, the EEBL message should contain all the necessary information for the following vehicles to make a reliably decision. In particular, the EEBL incoming message can include relevant message elements that describe the dynamics of the situation, a vehicle path history (also known as breadcrumbs) and other vehicle identifying data. It has been proposed that the path history (i.e. breadcrumbs) be defined by ten breadcrumbs with 1 sec time difference between subsequent breadcrumbs. Each breadcrumb contains location information of the vehicle so that the following vehicles can determine the relevancy of the incoming EEBL message. One problem with using breadcrumbs in making the relevancy determination of the incoming EEBL message is that the location information may not be sufficiently accurate to allow the following vehicles to know precisely the lane of the broadcasting vehicle.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved vehicle on-board unit that provides more precise lane information. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.